Second for me would be the epic Giants G1-3, Drow D1-3, and ending with Q1 Queen of the Demonweb Pits
Its kind of silly but I also liked running EX1-2 Dungeonland and Magic mirror. Based on Alice and Wonderland.
I like just abut everything in World of Greyhawk and was never a big fan of the other worlds.
The previously mentioned Expedition to the Barrier Peaks was a blast. That was really Metamorphosis Alpha in the D&D world.